Ticks are quite frustrating animals and they’re a big issue – especially in the springtime. As soon as temperatures rise above eight degrees Celsius for a few days straight, ticks become active. Whether it’s summer or winter, these bloodsucking invertebrates can become active enough for you to have your hands full, even at otherwise low temperatures.
A tick bite with consequences
30 January 2024 — by Linn Masch
Ticks and the possible transmissible diseases it may make you have to deal with – what you should be on the lookout for.
As soon as ticks leave their hiding places with the slight temperature increase, they begin to search for potential hosts. Tick eggs survive during mild, frostless winters, which results in the risk of ticks all year round and a particularly big menace during the spring and summer months. Since many ticks carry pathogens, the risk of infection increases for humans and animals alike as soon as the weather gets just that tad warmer.
Tick species
The most common ticks to keep an eye out for are leather ticks, shield ticks and alluvial forest ticks. The most common in Central Europe is the common wood tick, Ixodes ricinus. It is a vector of numerous zoonotic pathogens such as Borrelia and the TBE (tick-borne encephalitis) virus. Like all ticks of the family Ixodidae, the females suck blood as larvae, nymphs and adults. The host range of the common wood tick is broad, including up to 300 vertebrate species ranging from mammals to birds and reptiles. The risk for transmission of a variety of pathogens to different hosts is therefore the greater.
Dermacentor reticularis, the alluvial tick, is now also found in Central Europe and is primarily a vector of Babesia. Furthermore, it is associated with the transmission of Theileria equi, Q fever and the TBE virus.
The brown dog tick, Rhipicephalus sanguineus, is responsible for transmission of ehrlichiosis, hepatozoonosis, and a form of babesiosis. It is endemic from North Africa to France and has so far been reported in isolated cases in Germany.
The mild winter months and warm, humid summers allow the ticks to expand their habitats geographically and to remain active for longer periods of time. It can thus be assumed that tick species previously unknown in Germany can now be migrating here. Especially as we know that the distribution of ticks towards the north as well as to higher elevations has been steadily increasing over the last years.
Tick species in Europe
- Ixodes ricinus – common wood tick
- Dermacentor reticulatus – alluvial tick
- Rhipicephalus sanguineus – brown dog tick
Diseases transmissible by ticks
- Anaplasmosis
- Babesiosis
- Lyme disease
- Ehrlichiosis
- TBE (early summer meningoencephalitis)
Anaplasmosis
Ixodes ricinus is the causative agent and carrier of granulocytic anaplasmosis, although it can also be transmitted by blood transfusion. Therefore, before any blood transfusion, a certified health status and blood group testing is essential. Anaplasma phagocytophilum are unicellular blood parasites that infect some white blood cells, whereby the parasites multiply and destroy the cells. Transmission of the bacteria occurs only within 36 to 48 hours after the tick has attached. The clinical picture of anaplasmosis is characterized by an altered blood count, combined with nonspecific symptoms such as fever, inappetence and splenomegaly. The blood count shows thrombocytopenia and often leukopenia or leukocytosis. In addition, elevated liver enzymes and decreased albumin concentration may be observed. More importantly, even after surviving the acute phase of anaplasmosis, the host continues to harbor the pathogen, meaning that various stimuli or other diseases may cause a new outbreak of anaplasmosis.
Symptoms
- Hyperthermia
- Inappetence
- Joint inflammation featuring symptoms of lameness
- Thrombocytopenia
Diagnosis
- Blood smear
- PCR
Treatment
Ananplasmosis can be treated with tetracyclines for a period of four weeks.
Babesiosis
Alluvial and brown dog ticks are transmitters of babesia: Babesia canis in dogs and Babesia caballi in horses are transmitted by the tick bite, although transmission can also happen through blood transfusions. The babesia infect and destroy the erythrocytes of the host 12-72 hours after the tick bite. This results in a diminished oxygen transport in the organism.
Symptoms
- Fever
- Apathy and inappetence
- Edema
- Vomiting and diarrhea
- Hemolytic anemia
- Hemoglobinuria
- Icterus (jaundice)
- Acute renal failure
Diagnosis
- Blood smear
- PCR
- ELISA
Treatment
Imidocarb is used for prophylaxis and therapy of babesiosis in dogs, horses and cattle.
Lyme disease
Lyme disease is an infectious disease caused by the bacteria Borrelia. The main vector of Borrelia is the common wood tick. Borrelia lives in the intestines of ticks and is activated after the tick ingests blood. Therefore, the transmission time of the Borrelia to the host can persist for up to 24 hours after the tick's attachment. Borrelia can infect dogs, cats, horses, cattle and wild animals – as well as humans. The potential symptoms are varied and a diagnosis based solely on clinical symptoms is not possible. In contrast to the infection in humans, Erythema migrans is not seen in animals.
Symptoms
- Dogs: fever, swelling of lymph nodes, inappetence, joint inflammation
- Horses: lameness, fever, eye disorders, neurological deficits
Diagnosis
- ELISA
- Western blot
- PCR
Treatment
Early initiation of antibiotic treatment for Lyme disease is crucial as Borrelia bacteria are sensitive to tetracyclines and penicillins.
TBE
Early summer meningoencephalitis is a disease caused by the flavivirus. In Germany, the viral pathogen is mainly transmitted by the common wood tick (Ixodes ricinus). This tick can trigger meningitis and encephalitis with accompanying damage to the central nervous system. Affected animal species include dogs, cats, and horses. However, unlike humans, they rarely become ill as the disease in dogs is often subclinical. However, some symptoms may occur, nonetheless.
Symptoms
- Fever
- Increased sensitivity/pain
- Behavioral changes
- Signs of paralysis
Diagnosis
- PCR
- ELISA
In the early phase of the disease, the virus can be detected in the blood; subsequently, the virus can be detected in the cerebrospinal fluid.
Treatment
So far, no effective therapy is known.
Ehrlichiosis
Ehrlichiosis is caused by gram-negative coccoid bacteria, the Ehrlichia. These belong to the genus Rickettsiae. Ehrlichia are transmitted by the tick bite of the brown dog tick, although transmission via blood transfusion is also possible. Ehrlichia canis affects monocytes and spreads through the lymph nodes to the spleen and other organs. Depending on the type of pathogen and the animal species affected, different cell types may be affected.
Symptoms are wide-ranging, for example:
- Intermittent fever
- Inappetence
- Dyspnea
- Hemorrhages
- Lymphadenomegaly, splenomegaly
- Uveitis
- Vomiting
- Thrombocytopenia
- Hyperproteinemia
Diagnosis
- Blood smear
- PCR
Treatment
No pathogen-eliminating treatment is yet known, but infection can be treated with doxycycline or oxytetracycline for a period of four weeks.
Prophylaxis - tick protection
- Daily tick removal
- Prevention against tick infestation
- Vaccination, in risk areas and with an approved vaccine
Tick prophylaxis is the go-to for protecting your patients from these transmittable diseases and to prevent ticks from biting in the first place. The use of repellents, as spot-on preparations, is recommended. These preparations are also effective against mites, mosquitoes and fleas. In addition, regular inspections for a possible tick infestation is important. Remove ticks as quickly as possible. The risk of infection transmission increases with the duration of the ticks ingestion. Avoid designated tick biotopes and avoid risk areas during high infestation period between April and September. Due to milder yearly temperatures, year-round tick protection is advisable.
